The present invention relates to a device for transmitting electrical energy from an agricultural utility vehicle to an attachment which can be detachably attached to the utility vehicle.
Agricultural utility vehicles such as, for example field choppers, self-propelling spraying devices and tractors are known from the prior art. A tractor is a versatile utility vehicle since different attachments can be coupled to a tractor. Ploughs, harrows, grubbers, seeders, spraying machines, rotary mowers and round balers are usually coupled. Accordingly a tractor with a respectively coupled attachment carries out a wide variety of agricultural working functions. This makes it also necessary for the tractor to actuate the respective attachment in a corresponding way if the agricultural working function which is carried out with the attachment is carried out with an actuator, a tool or with a motor. But also different harvesting attachments for a combine harvester can constitute an attachment which requires individual actuation by the combine harvester.
Attachments are known whose actuators or tools are driven mechanically, wherein mechanical driving power is transmitted to the attachment from a power take-off shaft provided on the tractor. An example of such an attachment is a round baler. Furthermore, attachments are known which are driven hydraulically. For this purpose, hydraulic quick-release couplings are provided on the tractor and are connected to hoses of the attachment. Such an attachment is, for example, a front loader or a towed spraying machine. In the case of the front loader, the boom is controlled and activated hydraulically. In the case of the pulled spraying machine, the linkage is adjusted hydraulically.
Both the mechanical and the hydraulic transmission of power between the utility vehicle and the attachment entail problems in terms of actuation. It is therefore necessary, inter alia, for the internal combustion engine of the utility vehicle to be operated at a certain rotational speed and/or for the gear mechanism to have a certain, predefined transmission ratio to enable the attachment which is actuated via the power take-off shaft to be operated correctly. This may result in a poor level of efficiency of the tractor-trailer combination composed of the utility vehicle and attachment.
Attachments are known which have electrical loads. These are electric motors and/or fans of relatively low power class. Furthermore, lighting devices and/or solenoids can be operated electrically as actuator drives. Hitherto they have been supplied by the vehicle on-board electrical system of the utility vehicle. Electrical energy which is necessary for this is generated by the conventional dynamo of the utility vehicle. Hitherto, attachments with electrical loads which have a relatively high power consumption for carrying out an agricultural working function have not been used.
EP 1 306 955 A2 discloses a mobile high-voltage power system of a utility vehicle for making available direct voltage with a high power for an attachment. In this context, only direct current is transmitted via the attachment interface of the utility vehicle or of the attachment. However, this entails problems owing to corrosion and formation of light arcs.
WO 2006/114437 A1 discloses an interface device for transmitting electrical energy between a utility vehicle and an attachment which can be coupled to the utility vehicle. The interface device is assigned a measuring device and/or an actuating device. At least one electrical status variable of the transmitted electrical energy is quantified by means of the measuring device. At least one electrical status variable of the transmitted electrical energy is changed by means of the actuating device. Specifically, the voltage and/or the current strength of the transmitted electrical energy is increased or reduced by means of the actuating device, or the interface device is switched to a voltage-free state.
The present invention is based on the object of specifying and developing a device of the type mentioned at the beginning which overcomes the abovementioned problems. In particular, the intention is that the device will permit electricity to be supplied to an attachment which can be coupled to the utility vehicle, in which case the attachment is to be controlled more flexibly or better when it is operating, and the level of efficiency is to be raised.
Thus, the problem to be solved by the present invention is that of providing a device that will permit electricity to be supplied to an attachment for being coupled to an utility vehicle, in which case the attachment is to be controlled more flexibly or better when it is operating, resulting in the level of efficiency being raised.